Apparatus for automatically controlling traffic



Sept. 6, 1949. c. V.-LAWS APPARATUS FOR AUTOMATICALLY CONTROLLING TRAFFIC Filed July 1, 1946 mm mm, \M

QM mu Patented Sept. 6, 1949 UNITED STATES PATENT OFFICE APPARATUS FOR AUTOMATICALLY CONTROLLING TRAFFIC Claude'V. Laws, Rosemead, Calif. Application July 1, 1946, Serial No. 680,607

3 Claims. 1

This invention relates to an apparatus for automatically controlling traflic.

This invention is an improvement on apparatus shown in my copending application filed October 9, 1944, Serial No. 557,735, now abandoned. The copending application referred to discloses and describes a process and apparatus designed for keeping traffic moving continuously in all directions and at a uniform speed. In order to provide a trafiic controlling system in which the trafiic is intended to be in movement at all times, it is necessary to locate signals not only at the intersections of streets but at regularly spaced intervals between intersections and to change these signals from red to green progressively in the direction of the intended travel.

For such a trafiic-controlling system it is required that each signal be provided to not only display the red and green signals and for changing these signals at regular intervals, but each signal is required to have means for effecting these changes, which means are driven in synchronism with each other signal but at slightly different phases. That is to say, while each signal progressively up the street undergoes accurately the same succession of time intervals, the phases or times at which each of these signals starts, must vary up the street and the signals must be capable of being set to allow accurate control of this progressive time or phasing of these signals.

It is the general object of the present invention to provide a traffic controlling system in which means are provided by which each of a plurality of signals may have a speed of operation controlled simultaneously from the central station while each individual signal has its phase of operation capable of accurate, independent control.

Another object of the present invention is to provide an apparatus in which signals may be operated from a master station at different de sired phases, in which the driving means for the signals are motors and in which signal impulse means are provided for synchronizing the motors during operation.

Another object of the present invention is to provide motor-operated traffic control systems for progressive, continuous trafiic movement, in which the speed of movement of the traffic may be automatically varied from the central station.

Various further objects and advantages of the present invention will be apparent from the following description of a preferred example of a trains-controlling system embodying the present invention. For that purpose reference is hereinafter made to the accompanying drawings, in which Figure 1 is an electrical diagram.

Figure 2 is an elevation, partially in section, of the signal-phasing means.

Figure 3 is an elevation .of the phasing dial.

Figure 4 is a plan view of the light-control cam.

Figure 5 is a plan view showing the timing cam.

Referring to the drawings, the apparatus comprises a central control station which includes that portion of the apparatus diagrammatically illustrated at the left of the broken lines in Fig. .l. The apparatus also comprises individual signalcontrolling stations which are constructed in accordance with that portion of the apparatus illustrated to the right of the broken lines in Fig. 1. It is to be understood that while I have illustrated only one signal control station, in actual practice there will be a multiplicity of such stations, each of duplicate construction. Since the construction of each of the other stations is identical with that illustrated, it is believed that the illustration of one should be sufficient.

In practice, there will be a succession of signals on each side of the street to be served by the system, each having the apparatus hereafter to be described, located at intervals (and not only at intersections) at about feet or so progressively up the street, all as more particularly pointed out in my copending application previously referred to.

In the drawings, 2 and 3 are indicated as representing a pair of .A. C. power mains. The main 3 may be considered, for convenience, as a ground line. The central station includes three switches 4, 5 and 6, each connected to the main 2 at side. There 'is also provided a synchronous motor I which is connected to drive a cam 8 adapted .to close the circuit breaker 9 once each revolution. Means are provided for changing the speed at which the motor 1 drives the cam 8 in order to vary the speed at which the traffic is intended to move along the street. For example, the cam 8 may be designed to rotate 1 revolutions per minute, or once each 40 seconds, when operating at high speed and may be intended to operate at a low speed where the cam rotates only one revolution per minute. These changes in the speed of driving the cam 8 from the motor 1 are efiected by energizing the relay It]. The relay I 0 operates to shift the gear relation between the motor 1 and cam 8 through the use of the gearshift mechanism la shown in Fig. 2, and hereafter more particularly described in connecmain 2. Line l leads to the coil of relay l2 which is connected by line IE to the ground 3.

closed connects line I5 to the ation actuated by an arm 42 pivoted to the case and exteriorly of the housing positioned to be actuated by the magnet of relay 24. In Fig. 2 is also shown the pivotal mounting of the circuit breaker 25. A spring, such as indicated at 43, may be provided for normally maintaining the double-acting clutch in the high speed position.

At each of the signals the shaft 40, driven by the motor, is provided with a timer-actuating cam member 44 and with a light-actuating cam j member 45. Cam 44 actuates the contact arm 46 Closing of switch 4 also connects line 2 to line ll leading to one of the contacts of, the breaker H so that when this is supplied to the relay iii to change the speed of motor I. The contact ll thus operates as hereafter described in a self-holding circuit. The closing of switch 4 also connects the synchronous motor 1 across the mains 2 and 3 so that the synchronous motor starts its operation. Simultaneously there is energized the line it which is one of the leads from the-central station to each of the signals of the system. Of the three signalling lines connecting the central station with each of the signals, one is the ground line 3, another is the line 18, and another is the line H? which is adapted to be connected to main 2, either directly by means of switch 6, or once each revolution by closing of the breaker 9- provided switch 5 is closed.

Switch 5 when closed connects a line to the circuit-breaker 9 and a line 2| to the breakers l3 and i4, and hence, provided relay i2 is not energized, to line 22 leading to the speed change coil of relay [0.

The three lines 3, IS and 99 are common lead lines to each of the signals of the system, and each of the signals includes a synchronous motor 23, which synchronous motor should be identical to the motor I in the master station, or at least have the same speed of operation and the same means for changing the speed of operation. The motor 23 is provided with a relay 24 for changing the speed at which the motor drives certain control cams 44 and 45. For this pur pose the relay as hereafter more particularly described in connection with Figure 2 actuates a gearshift 24a. The relay 24 operatesa self-holding contact or breaker 25. At each station there is also provided a relay 26 for opening the normally closed circuit breakers 28 and 29. There is also provided a green light 30, a red light 3!, and a phase indicator 33.

Now referring more particularly to Fig. 2 of the drawings, I have shown one type of apparatus which might be employed for shifting the speed of operation of the motors, such as indicated at 23 in the signals, or at l in the central sta tion. As there indicated, the motor which for the purpose of illustration may be the motor 23, is adapted to drive the gear 34 connected to the shaft 35. Shaft 35 mounts a relatively large and relatively small gear 36 and 31, respectively, which are in turn connected to a relatively small and relatively large gear 38 and 39 mounted upon a shaft 4i) and adapted to be connected to that shaft by the double-acting clutch 4!. When the double-acting clutch 4! is moved to the right, as indicated in the figure, gears 36 and 38 are connected to the shaft to allow for the high speed operation, and when moved to the left, gears 31 and 39 are connected, allowing for the slow speed of operation. The double-acting clutch is in oper= 15 breaker is closed current which is indicated as connected by line 41 to the motor 23. Normally, this arm 46 is in contact with contact 48 which is connected to line 49 connected to the lead l8. Once each revolution of the timer cam the timer cam is adapted to open the connection between contact 48 and arm 46 and close arm 46 against a contact 50 connected to a lead 5! connected with the synchronizing main l9.

In order to control the phase of operation of the timer earn the timer cam is provided with a dial control means. As indicated in Fig. 2, the

, indicating dial 52 is rigid with the shaft and 'contact 5'! or contact 58.

the cam 44 is movable into various rotary positions relative to the dial :32 by means of an arm 53 which has an indicating pointer 54 for indicatin the adjusted positions relative to a scale provided on the dial 52. Friction may be sufficient to set the cams at any adjusted position,

or any desired method may be provided for latching the parts in the relative adjustable positions.

The light cam 45 is designed, as indicated, to move the contact arm 56 into contact either with The light cam 45 is preferably designed so that in the larger portion of the cycle of operation, the cam will position the arm 55 in contact with contact 58. For example, the particular cam indicated is one for which 225 rotation contact will be made with contact 58 and only 125 of rotation will contact be made with contact 5?. The arm 56 is connected to contact 48 of the timer member 18 of the main. The number 58 contact leads to the red light 3 i, while number 51 contact leads to the green light 30. The opposite sides of both the red and green lights are indicated as connected to the ground 3. The contact arm 56 line is adapted to make contact with contact 59 in its lower position, which is connected by a lead 60 with the phase indicator 33.

In the operation of the apparatus of the present invention, when it is desired to operate the system on the fast speed of operation, switch 4 is closed. This closes relay l2 at the central station and all of the relays 26 of the individual signals. Simultaneously this starts operation of the motor 1 in the central station. and simultaneously starts all of the motors 23 of the different signals. The motors of the individual signals are all started simultaneously with the motor I for the reason that arm 46 is then in contact with contact 48, and the circuit may be traced from main 2 through switch 4, line l8, to line 49, to contact 48, arm 46 to line 4'! to motor 23, and hence to the ground lead 3. Simultaneously the current is supplied to either the green or red light of the individual signals. The circuit for this is traced from main 2 through switch 4, line !8, contact 48, arm 46 to arm 56 of the timer cam and hence alternately either through contact 5'! to the green light or contact 58 to the red light of the signal.

It will be understood that the phases of different signals are individually adjusted by adjusting the position of the arms 53 relative to the dials in order to provide the desired progessive shifting of the signals.

If only switch number 4 is closed, the operation will continue for a single revolution, whereupon arm 46 will separate from contact 48, disconnecting both the signals and the motors of the signals from the mains. Immediately, however, after closing switch number 4, switch 5 is also closed, which applies current to line 20, to the contact 9 operated by motor 1 of the master station. Provided motors 23 of the individual signals are in synchronism with the motor I of the master station, the closing of contact 9 will correspond precisely to the separation of arm 46 from the contact 48 and the closing of contact 50. In such an event power is continued for operation of the motors 23 and the signals through a circuit which may be traced through main 2, through switch 5, contact 9, contact 50, arm 46 and hence to both arm 55 and the signals or to the motors 23 of the signals. If, however, signal motor 23 actuates its timer cam previous to the actuation of the timer cam 8 of the master station, there will be an interruption in the movement of the motors 23 of the signals to compensate for this excessive speed of operation so that the motors of the signals at central station are each positively synchronized with each other once during each revolution.

When it is desired to operate the signalling system on low speed, switches 4 and 5 are open and thereafter switches 5 and 5 close. The closing of switch 5 with switch 4 open, applies current from the main 2 through the contacts I3 and I4 of relay l2 (which are closed when switch 4 is open) to the relay Hi of the master switch which actuates the speed control mechanism and in a similar manner closing of switch 6 connects line l9 through contacts 28 and 29 now closed, to the speed change magnet 24 of the signal motors to low speed (for example, by actuation of the double-acting clutch described).

It is also to be understood that contact I l at the master station and contact 25 at each signal, are closed, which will provide self-holding circuits for the speed control relays l and 24 when, as hereafter pointed out, switch 4 is closed. Switch 4 is now closed, which in addition to completing the self-holding circuits mentioned, allows the flow of current to the motors in the manner herein described, the operation being identical with that previously described, except that the motors at the central station and the motors of the signals operate now under low speed conditions. Promptly on closing switch 4, switch 6 is open so that line 20 is again under the control of the timer cam 44 of the master station.

When it is desired to shut off the operation of the system, switches 4, 5 and 6 are opened and thereafter switch 6 alone closes. When one switch member 6 is closed, line I 9 is connected to main 2. The signal ceases operating whenever the timer cam arm 46 separates from contact 50.

While the particular form of the apparatus herein described is well adapted to carry out the objects of the present invention, various modifications and changes may be made, but this invention is of the scope set forth in the appended claims.

I claim:

1. An apparatus for synchronizing a motor of a trafiic signal with the movements of a central motor, which apparatus comprises cam-actuated means driven by said signal motor and in cluding two circuit breakers adapted to be simultaneously operated, one to open while the other closes, a driving circuit for said signal motor which includes one of said circuit breakers, a circuit breaker actuated by said central motor, and a supplemental driving circuit for said signal motor including said latter circuit breaker and the other circuit breaker actuated by the signal motor whereby, when the first-mentioned driving circuit is opened, said supplemental driving circuit is adapted for driving said motor, provided the motors are in synchronism so that both of the circuit breakers in said supplemental circuit are closed.

2. An apparatus for synchronizing a motor of a trafiic signal with the movements of a. central motor, which apparatus comprises cam-actuated means driven by said signal motor and including two circuit breakers adapted to be simultaneously operated, one to open while the other closes, a driving circuit for said signal motor which includes one of said circuit breakers, a circuit breaker actuated by said central motor, and a supplemental driving circuit for said signal motor including said latter circuit breaker and the other circuit breaker actuated by the signal motor whereby, when the first-mentioned driving circuit is opened, said supplemental driving circuit is adapted for driving said motor, provided the motors are in synchronism so that both of the circuit breakers in said supplemental circuit are closed, and means for shifting the phase with which said signal motor operates its circuit breakers.

3. In a traflic control system of the type including a central motor and a motor at each signal, an apparatus for synchronizing the signal motors with a central motor, which comprises cam-actuated means driven by said signal motor, and including a circuit breaker normally closed, but opened once in each revolution of said signal motor, and the second circuit breaker normally opened, but closed once during each revolution of said signal motor simultaneously with opening the said first-mentioned circuit breaker, a main driving circuit for said signal motor which includes said normally closed circuit breaker, a normally open circuit breaker driven by the central motor and adapted to be closed once during each revolution of the central motor, and a supplemental driving circuit for said signal motor including said latter last-mentioned circuit breaker and the normally open circuit breaker actuated by the signal motor.

CLAUDE V. LAWS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,951,816 Bechtold Mar. 20, 1934 2,091,954 Bissell Sept. 7, 1937 2,328,473 Leonard Aug. 31, 1943 

